This will be a comprehensive program to improve the characteristics and use of gutta-percha as a root canal filling material utilizing the combined principles of endodontics, engineering and statistics. Commercially available gutta-percha will be subjected to a complete series of tests, many of which will be an adaptation of currently used plastic test methods. Extensive use will be made of the Scanning Electron Microscope. Special efforts will be made to investigate the effect of various storage conditions and to improve shelf life. Other tests will simulate clinical conditions. Program should result in a gutta-percha more suitable for clinical use and that will be a more effective filling material. Specifications defining composition and characteristics as well as appropriate test equipment will be developed. Recommendation will be made for improvement of clinical procedures.